/*
 * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.oracle.java.testlibrary.compiler;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

import javax.tools.JavaCompiler;
import javax.tools.StandardJavaFileManager;
import javax.tools.StandardLocation;
import javax.tools.ToolProvider;

/**
 * This class consists exclusively of static utility methods for invoking the
 * java compiler.
 */
public final class CompilerUtils {
    private CompilerUtils() {
    }

    /**
     * Compile all the java sources in {@code <source>/**} to
     * {@code <destination>/**}. The destination directory will be created if
     * it doesn't exist.
     * <p>
     * Equivalent to calling {@code compile(source, destination, true, options);}.
     * <p>
     * All warnings/errors emitted by the compiler are output to System.out/err.
     *
     * @param source      Path to the source directory
     * @param destination Path to the destination directory
     * @param options     Any options to pass to the compiler
     * @return true if the compilation is successful
     * @throws IOException                   if there is an I/O error scanning the source tree or
     *                                       creating the destination directory
     * @throws UnsupportedOperationException if there is no system java compiler
     */
    public static boolean compile(Path source, Path destination, String... options)
            throws IOException {
        return compile(source, destination, true, options);
    }

    /**
     * Compile all the java sources in {@code <source>} and optionally its
     * subdirectories, to
     * {@code <destination>}. The destination directory will be created if
     * it doesn't exist.
     * <p>
     * All warnings/errors emitted by the compiler are output to System.out/err.
     *
     * @param source      Path to the source directory
     * @param destination Path to the destination directory
     * @param recurse     If {@code true} recurse into any {@code source} subdirectories
     *                    to compile all java source files; else only compile those directly in
     *                    {@code source}.
     * @param options     Any options to pass to the compiler
     * @return true if the compilation is successful
     * @throws IOException                   if there is an I/O error scanning the source tree or
     *                                       creating the destination directory
     * @throws UnsupportedOperationException if there is no system java compiler
     */

    public static boolean compile(Path source, Path destination, boolean recurse, String... options)
            throws IOException {
        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        if (compiler == null) {
            // no compiler available
            throw new UnsupportedOperationException("Unable to get system java compiler. "
                    + "Perhaps, jdk.compiler module is not available.");
        }
        StandardJavaFileManager jfm = compiler.getStandardFileManager(null, null, null);

        List<File> sources
                = Files.find(source, (recurse ? Integer.MAX_VALUE : 1),
                (file, attrs) -> (file.toString().endsWith(".java")))
                .map(e -> e.toFile()) // use jdk1.8
                .collect(Collectors.toList());

        Files.createDirectories(destination);
//        jfm.setLocation(StandardLocation.CLASS_PATH, Collections.emptyList()); comment out , use jdk1.8, backport from jdk11u
        jfm.setLocation(StandardLocation.CLASS_OUTPUT,
                Collections.singletonList(destination.toFile()));

        List<String> opts = Arrays.asList(options);
        JavaCompiler.CompilationTask task
                = compiler.getTask(null, jfm, null, opts, null,
                jfm.getJavaFileObjectsFromFiles(sources)); // use jdk1.8

        return task.call();
    }
}
